1. Field of the Invention
This invention relates generally to devices for the treatment of diseased hearts and more particularly to synthetic intraventricular heart implants and assist devices, and a method for inserting the same.
2. Description of Related Art
As is well known, the human heart has four main chambers. Of these chambers the left and right ventricles can be affected by many diseases that may need to be corrected by surgical procedures. By way of example only, and not for reasons of limitation, the present invention will be described with respect to the left ventricle of a patient's heart, from which blood is pumped into the aorta and then into the arteries of the human body. However, it is to be understood that the present invention is also applicable to the right ventricle (when assist devices are needed).
Recent studies have shown that many patients who suffer from heart diseases, such as arteriosclerosis with left or right ventricular dysfunction, and the like, and who undergo some type of revascularization surgery are provided with relief from angina. However, such revascularization procedures generally fail to improve ventricular function, particularly if a patient's left ventricle is enlarged. Such patients, therefore, continue to deteriorate with eventual heart failure, resulting in increased mortality and reduced chances of survival. This occurs, because of the increased end- diastolic volume and pressure, and low ejection fraction (expulsion of blood) from the left ventricle.
Medical therapy, after such revascularization procedures, with diuretics and ACE inhibitors, helps some patients, but does not significantly reduce mortality, nor does it increase the survival rate for patients. Therefore, there is a long standing need for a device and/or method to increase the survival rate of patients suffering from left ventricle enlargement and dysfunction, as well as other heart diseases, which require surgery.
While left and right ventricular assist devices and methods of using them are known, these known devices and methods only bring about limited relief in certain circumstances. These known devices and methods are not usually for permanent placement within the heart, nor do they satisfactorily produce results in all patients and/or all circumstances. Therefore, there still exists the need in the medical art for a device and method which may be used to permanently aid those patients who are suffering from heart diseases, such as, but not limited to, arteriosclerosis with left ventricle dysfunction in which evasive revascularization surgery must be performed.
One known assist device is shown in U.S. Pat. No. 4,573,997, which discloses a right ventricular assist device for aiding the circulation of blood from the right ventricle, for a predetermined time, until the patient's heart recovers sufficiently to remove the assist device. The device includes a smooth segmented sac having a single, valveless passageway/inlet and outlet. The sac is surrounded by a rigid ellipsoidal shell with a first opening for the inlet/outlet of the sac and a second opening for pressurizing a separate interior portion of the shell. A flexible diaphragm extends across the interior of the shell to divide the interior into two unequal volumes, with the sac and the first opening in a first and larger volume, and the second opening and a pressurizing chamber in a second and smaller volume. The diaphragm expels approximately 90% of the blood held in the sac when the smaller chamber is pressurized. The device is attached to the pulmonary artery of a patient and, therefore, is not useful in a ventricle, nor can it be inserted into the heart of a patient.
U.S. Pat. No. 4,685,446, discloses a method and device to assist the left ventricle of a patient, consisting of an inflatable balloon connected at the distal end of a single lumen catheter that is inserted into the left ventricle of the patient, and a pump at the proximate end of the catheter, to inflate and deflate the balloon by means of a fluid, upon receipt of an electronic signal that coincides with ventricular systole and diastole, to augment ejection of blood from the left ventricle. This device is a temporary device that requires insertion through the arteries of a patient, is not implantable, and both the device and the method disclosed therein do not, among other things, take into account the problems that occur because of weakened wall portions of a ventricle.
U.S. Pat. Nos. 4,771,765 and 4,902,273 are related to U.S. Pat. No. 4,685,446, discussed above. Both of these patents disclose similar assist devices and methods to assist the left, or both the left and right ventricles of the heart of a patient. However, the devices disclosed in these two patents include either one or two balloons connected at one or two distal ends of a two lumen catheter inflatable by a first lumen in the catheter, as well as an intraaortic balloon located between the proximal and distal end (or ends) of the catheter and inflatable by the second lumen. If only one distal balloon is used, it is inserted into the left ventricle, however, if two distal balloons are used, they are inserted into both the left and the right ventricles. A pumping mechanism, having two pumps, is provided at the proximate end of the catheter, to inflate and deflate the balloons on the devices by means of a fluid, at pre-determined times. These devices and methods are complicated, and suffer from the same drawbacks as U.S. Pat. No. 4,685,446.
U.S. Pat. No. 4,995,857, discloses a left ventricular assist device and method to relieve the hemodynamic burden on a diseased left ventricle by inserting a shunt having an impeller for substantially non-turbulent, non-traumatic flow of blood either from the left atrium or the patient's venous system, directly into the patient's arterial system. The device of this patent may be implanted temporarily or permanently in a patient, to by-pass the left ventricle, but is not an intra-ventricular device, and is always implanted exteriorly of the heart itself.
The above-mentioned devices and methods provide limited improvements for certain heart diseases, as described in the respective patents. However, the devices and methods of these patents fail to adequately work in all patients under all circumstances, tend to be complex, are not implanted within a ventricle of a patient, and are limited to the specific applications set forth therein.